Issue 37 - It's all going down the tubes

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It's all going down the tubes

Ian Wisniewski compares the merits of worms against those of shell and tube condensers

If only I'd been taught chemistry on the basis of how malt whisky is distilled, I wouldn't have spent so many years ignoring the teacher. Always an arts swot and never a scientist, I've got a lot of homework to do now that malt whisky has added meaning to my life.

Although I still consider malt whisky to be a work of art, I have to concede that it can't happen without some science. And one of the most intriguing, not to mention challenging, topics is the influence of copper.

Investigating copper tends to focus on its role in the stills, with copper absorbing sulphur compounds, and converting them into other, less organoleptically active compounds (ie. less sulphur character), while also acting as a catalyst that helps to manipulate the ester character.

As sulphur compounds are conveyed in the form of struck matches, sulphurous, rubbery, meaty and sweaty socks, not to mention cabbage and vegetal notes, they can easily ‘conceal' other characteristics within the new make spirit.

While a certain level of sulphur character can be highly desirable, according to the house style, lowering the level of sulphur compounds allows the congeners, including esters, to show more readily.

But the copper debate isn't complete without considering the type of condenser, which also influences the new make spirit.

A shell and tube condenser provides a greater surface area of copper, and consequently an increased degree of copper contact, compared to a worm.